A speaker is driven by an amplifier. A speaker comprises an inductive load on the amplifier. As such, a phase difference exists between current through and voltage to the speaker. Some amplifiers are Class-D amplifiers which include a switching regulator. The voltage on an output terminal of a Class-D amplifier becomes negative in a recycle mode for the amplifier. That is, for a speaker amplifier operated from a power supply and ground, one node or the other of the speaker may experience a negative voltage.
Negative voltages on the speaker nodes poses a problem for systems which measure speaker current. The measure of speaker current can be used to assess speaker temperature and excursion. Negative voltages cause complications for switches connected to sense nodes on the output of the amplifier. Such switches may experience leakage current due to the negative voltages, which in turn causes accuracy, linearity and total harmonic distortion and noise problems.